<template>
  <div>
    <router-link
      v-show="showAbs"
      tag="div" to="/"
      class="header-abs">
      <div class="iconfont header-abs-back">&#xe624;</div>
    </router-link>
    <div class="header-fixed"
         v-show="!showAbs"
         :style="opacityStyle">
      <router-link to="/">
        <div class="iconfont header-fixed-back">&#xe624;</div>
      </router-link>
      景点详情
    </div>
  </div>
</template>
<script>
export default {
  name: 'DetailHeader',
  data () {
    return {
      showAbs: true,
      opacityStyle: {
        opacity: 0
      }
    }
  },
  methods: {
    handleScroll () {
      const top = document.documentElement.scrollTop
      if (top > 60) {
        let opacity = top / 140
        opacity = opacity > 1 ? 1 : opacity
        this.opacityStyle = {
          opacity
        }
        this.showAbs = false
      } else {
        this.showAbs = true
      }
    }
  },
  activated () {
    window.addEventListener('scroll', this.handleScroll)
  },
  deactivated () {
    window.removeEventListener('scroll', this.handleScroll)
  }
}
</script>
<style lang="stylus" scoped>
  @import "~styles/varibles.styl"
  .header-abs
    position : absolute
    left :.2rem
    top :.2rem
    width :.8rem
    height :.8rem
    border-radius :.4rem
    text-align :center
    background :rgba(0, 0, 0, .8)
    line-height :.8rem
    font-size :.4rem
    .header-abs-back
      font-size :.4rem
      color :#fff
  .header-fixed
    z-index :2
    position :fixed
    top :0
    left :0
    right :0
    height :$headerHeight
    overflow :hidden
    line-height :$headerHeight
    text-align :center
    color :#ffffff
    background-color: $bgColor
    .header-fixed-back
      width :.64rem
      position :absolute
      top :0
      left :0
      font-size :.4rem
      text-align center
      color :#ffffff
</style>
